I think the cat 1 is the book to get...ff 66-67, Thor 165 vs. Marvel premiere 1 argument that has been going on here for a while now...
The Cat is the book to get for what? The Cat is not Hellcat. Greer Grant is Tigra, OK, so if you like Tigra you have to keep both the Cat mini-series and the Giant Size Creatures.
Aside from this, anyone still insisting on the relevance of Thor #165 (story wise) have just never read the stories (or deliberately want to ignore a 40+ years of comics history). A cool cover, whatever you want, but nothing more. The story is also inconsistent.
It's the one to get regarding bronze age books that are heating up on eBay...